The load balancer uses runnable_load_avg as load indicator. For
!cgroup this is:
runnable_load_avg = \Sum se->avg.load_avg ; where se->on_rq
That is, a direct sum of all runnable tasks on that runqueue. As
opposed to load_avg, which is a sum of all tasks on the runqueue,
which includes a blocked component.
However, in the cgroup case, this comes apart since the group entities
are always runnable, even if most of their constituent entities are
blocked.
Therefore introduce a runnable_weight which for task entities is the
same as the regular weight, but for group entities is a fraction of
the entity weight and represents the runnable part of the group
runqueue.
Then propagate this load through the PELT hierarchy to arrive at an
effective runnable load avgerage -- which we should not confuse with
the canonical runnable load average.
Suggested-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
---
include/linux/sched.h | 3
kernel/sched/debug.c | 8 ++
kernel/sched/fair.c | 173 ++++++++++++++++++++++++++++++++------------------
kernel/sched/sched.h | 3
4 files changed, 125 insertions(+), 62 deletions(-)
@@ -2931,31 +2949,45 @@ static long calc_cfs_shares(struct cfs_r
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
-static void update_cfs_shares(struct sched_entity *se)
+/*
+ * Recomputes the group entity based on the current state of its group
+ * runqueue.
+ */
+static void update_cfs_group(struct sched_entity *se)
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